>>33102043>>33102055>>33102076>>33102079>>33102101Anons inspired me to run some calculations. Turns out if Serperior is fully SpA EVed/Modest, Choice Specs, Contrary and Milotic is fully SpD EVed/Calm, Milotic survives Leaf Storm 62.5% of the time, and therefore OHKOs with Mirror Coat, and faints the other 37.5%. Should the Milotic have an item, say, an Assault Vest, it would always survive, and always OHKO with Mirror Coat.
So, standard matchup has Milotic winning 62.5% of the time, since there's never any reason not to use Mirror Coat against an obviously-Specs Serperior, and always wins if it gets to pick an item as well.
Considering type advantage and BST difference, this was way closer than I thought. But, statistically, Milotic will generally win vs a standard Contrary Serperior set even without AVest. Just in case anyone else cared about the specific numbers.